High-intensity, persistent photoluminescent formulations and objects, and methods for creating the same

ABSTRACT

Disclosed are photoluminescent formulations, comprising an effective amount of photoluminescent phosphorescent materials, which exhibit high luminous intensity and persistence. Also disclosed are photoluminescent objects formed by applying at least one photoluminescent layer, formed from photoluminescent formulations, to preformed articles. Further disclosed are methods for creating photoluminescent objects.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 60/637,535, filed Dec. 20, 2004 (Attorney Docket No.7044531001), titled, “Layered Envirochromic Materials, Applications andMethods of Preparation Thereof,” which is incorporated by referenceherein for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to photoluminescent phosphorescentformulations, comprising an effective amount of photoluminescentphosphorescent materials, that exhibit high luminous intensity andpersistence. The photoluminescent phosphorescent formulations mayfurther comprise photoluminescent fluorescent materials, wherein saidphotoluminescent fluorescent materials increase the luminous intensityand persistence. These photoluminescent fluorescent formulations mayfurther comprise photostabilizers to retard the photolytic degradationof said photoluminescent materials.

The present invention is also directed to photoluminescent objectscomprising at least one photoluminescent formulation and a preformedarticle. Further disclosed are methods for creating photoluminescentobjects comprising applying at least one photoluminescent formulationonto a preformed article.

2. Description of Related Art

Consumers have a continuing desire to receive added informationalfeatures and benefits from the products that they purchase. Suchinformation and features can comprise safety information indicators,environmental information indicators, shelf-life information indicators,authentication and tamper indicators, fashion accessory benefits and/orfun and entertainment benefits. Color-change technology triggered byspecific environmental events can form the foundation for creating theseinformational indicators or benefits. It is important to note that forthe utilization of color-change as informational indicators or providingadditional benefits to be effective, such color change needs to bevisually striking and for outdoor usage environmentally robust.

“Envirochromic Materials” and “Envirochromic Layers” are those, whentriggered by a specific environmental change or occurrence, that canchange their visible color which can result from either onset or changein electromagnetic radiation emission, and/or change in the absorptionreflection, and/or scattering of electromagnetic radiation. Theseenvironmental “triggers” include change in temperature, change inelectromagnetic radiation, change in chemical environment, an electricalstimulus, etc.

Since color change can occur from a multiplicity of triggers, the word“chromic,” as used herein, signifies a color change occurring fromchange in reflection, absorption, or scattering of electromagneticradiation. “Chromic,” as used herein, does not signify a color changeoccurring from change in emission. Thus, for example: photochromismsignifies color change triggered by electromagnetic radiation;thermochromism signifies color change triggered by change intemperature; electrochromism signifies change in color occurring due togain or loss of electrons; solvatochromism signifies color changeresulting from change in solvent polarity; halochromism signifies colorchange caused by a change in pH; ionochromism signifies color changecaused by ions; tribochromism signifies change in color caused by changein mechanical friction; and piezochromism signifies change in colorcaused by change in mechanical pressure.

As can be appreciated, color change can also result from luminescentemissions. For such a case, and being consistent with the definitionabove, “luminescent” or “luminous,” as used herein, signifies colorchange resulting from emissions.

The term “luminescence” is defined as the emission of electromagneticradiation from any substance. Luminescence occurs fromelectronically-excited states. As seen in FIG. 1, absorption ofultraviolet radiation by a molecule excites it from a vibrational levelin the electronic ground state to one of the many vibrational levels inthe electronic excited states. The electronic states of most organicmolecules can be divided into singlet states and triplet states.

As used herein, “singlet state” refers to when all electrons in themolecule are spin-paired. As used herein, “triplet state” refers to whenone set of electron spins is unpaired. The excited state is usually thefirst excited state. A molecule in a high vibrational level of theexcited state will quickly fall to the lowest vibrational level of thisstate by losing energy to other molecules through collision. Themolecule will also partition the excess energy to other possible modesof vibration and rotation.

“Luminescent materials” are those which emit electromagnetic radiation.Characterizing luminescent materials requires consideration of: (1) theexcitation source, (2) the nature of the emission, and (3) whether ornot additional stimulation is required to cause emission.

With regard to the excitation source, luminescent materials excited byelectromagnetic radiation are referred to herein as “photoluminescent.”Luminescent materials excited by electrical energy are referred toherein as “electroluminescent.”Luminescent materials excited by achemical reaction are referred to herein as “chemiluminescent.”

With regard to the nature of the emission, this may be eitherfluorescence or phosphorescence. A “fluorescent” material storeselectromagnetic radiation and releases it rapidly, in about 10⁻¹²seconds or less. Contrarily, a “phosphorescent” material storeselectromagnetic radiation and releases it gradually, in about 10⁻⁸secondsor more.

Processes that occur between the absorption and emission ofelectromagnetic radiation are usually illustrated using a JablonskiDiagram, such as the one found in FIG. 2. Ground, first, and secondelectronic states are depicted in FIG. 2 by S₀, S₁, and S₂,respectively. At each electronic energy level, the fluorophores canexist in a number of vibrational energy levels, denoted by 0, 1, 2, etc.Transitions between states are depicted in FIG. 2 as vertical lines toillustrate the instantaneous nature of electromagnetic radiationabsorption.

“Fluorescence” occurs when a molecule returns, by emission of a photon,from the excited singlet state to the electronic ground state. If thephoton emission occurs from S₁ to S₀, it is characterized asfluorescence.

“Phosphorescence” occurs when a molecule goes from the ground state to ametastable state such as T₁, a triplet state, and then the metastablestate slowly decays back to the ground state S₀, via photon emission.Hence, if the emission occurs between T₁ to S₀, it is characterized asphosphorescence.

With regard to whether or not additional stimulation is required tocause emission, as used herein, the need for “additional stimulation” isbased upon the predominant behavior of the material at about roomtemperature, i.e., at about 10° C. to about 35° C. Thus, in cases whereelectromagnetic radiation is used to stimulate emission at roomtemperature, such materials are referred to as “photoluminescentphoto-stimulable.” In cases where electrical energy is used to stimulateemission at room temperature, such materials are referred to as“photoluminescent electrically-stimulable.” In cases where thermalenergy is used to stimulate emission at room temperature, such materialsare referred to as “photoluminescent thermally-stimulable.”

The instant invention applies and uses photluminescent phosphorescentmaterials to cause nighttime emissions, which may additionally comprisephotoluminescent fluorescent materials to enhance the intensity andpersistence of the nighttime emission and/or the color of the daytimeand nighttime emissions.

In the past, metal sulfide pigments were used in an attempt to arrive atphotoluminescent phosphorescent materials. See, e.g., U.S. Pat. No.6,207,077 to Burnell Jones. A common such metal sulfide pigment is azinc sulfide structure whereby the zinc is substituted and activationoccurs via various elemental activators, coactivators, or compensators.Common activators include copper, aluminum, silver, gold, manganese,gallium, indium, scandium, lead, cerium, terbium, europium, gadolinium,samarium, praseodymium, and other rare-earth elements and halogens.These activators are believed to enter the crystal lattice of the hostmaterial and are responsible for imparting the luminescent properties tothe material.

Examples of sulfide phosphorescent phosphors include CaS:Bi, which emitsviolet blue light; CaStS:Bi, which emits blue light; ZnS:Cu, which emitsgreen light; and ZnCdS:Cu, which emits yellow or orange light. However,these sulfide phosphorescent phosphors are chemically-unstable and, as aresult, exhibit photolytic instability.

An extensively-used sulfide phosphorescent phosphor is zinc sulfide,ZnS:Cu. See, e.g., U.S. Pat. No. 3,595,804 to Martin. However, zincsulfide decomposes due to irradiation by ultraviolet radiation in thepresence of moisture. This decomposition reduces and/or blackens theluminance, making the use of zinc sulfide difficult in environmentscontaining ultraviolet radiation and/or moisture. As a result, zincsulfide is used most-commonly in controlled environments, such as forclock, watch, and instrument dials, and for indoor uses.

Relatively recently, see, e.g., U.S. Pat. No. 5,424,006 to Murayama,metal aluminate photoluminescent pigments, particularly alkaline earthaluminate oxides having the formula MAl₂O₄, where M is a metal ormixture of metals, have been developed. Examples of such alkalinealuminate oxides include strontium aluminum oxide, SrAl₂O₄, calciumaluminum oxide, CaM₂O₄, barium aluminum oxide, BaAl₂O₄, and mixturesthereof. These aluminate phosphors, with or without added magnesium, maybe further activated with other metals and rare-earth elements.

These aluminate photoluminescent pigments exhibit afterglowcharacteristics that last much longer in duration than do those of metalsulfide pigments. These aluminate photoluminescent pigments also exhibitstrong photolytic stability and are chemically more stable than themetal sulfide pigments. For example, strontium aluminum oxide, SrAl₂O₄,such as that disclosed in U.S. Pat. No. 5,698,301 to Yonetani, exhibitsluminance that is about five- to ten-times that of zinc sulfidephosphoresecent phosphor, ZnS:Cu, and exhibits a smaller decay rate.Strontium aluminum oxide also exhibits an emission spectrum having apeak wavelength of 520 nanometers (“nm”), which is near the spectrum ofpeak human visibility, and exhibits a broad excitation spectrum withhigh excitation efficiency to ultraviolet electromagnetic radiation inthe short wavelength region.

However, alkaline earth phosphors, such as strontium aluminum oxide,exhibit the disadvantage of requiring more excitation time to attainsaturation luminance than do metal sulfide pigments, such as zincsulfide phosphoresecent phosphor. In addition, alkaline earth phosphorshave the disadvantage of moisture sensitivity. On the other hand,sulfide-based phosphors degrade photolytically.

It can be appreciated that for optimal luminescent performance, specificphotoluminescent phosphorescent materials and mixtures of such materialsneed to be adapted for use in varying conditions, be it excitationconditions or environmental considerations. Water-resistant formulationssuitable for protecting the photoluminescent phosphorescent particlesand formulations that minimize photolytic degradation, particularlywhere metal sulfides are utilized, are sought-after. Beyond theselection of the photoluminescent phosphorescent materials and/or anyadditional photoluminescent fluorescent materials used to enhance theirperformance, it should be noted that the luminous intensity and/orpersistence from a photoluminescent formulation is greatly affected byboth the way in which the photoluminescent phosphorescent material isdistributed and the additives used, as well as the manner in which thatformulation is applied. As noted above, for these materials to serve ascolor-change indicators or to provide added information and/or benefitsto consumers, the color change needs to be visually striking to beeffective.

The improper selection and use of formulation materials, such as resins,dispersants, wetting agents, thickeners, and the like can diminish theluminous intensity emanating from the formulation. This can occur, forexample, due to agglomeration or settling of photoluminescentphosphorescent particles, either during handling of the formulatedmaterials or after application of the formulated materials. Thereduction in luminous intensity and/or persistence can result from bothincomplete excitations and/or due to scattering of emitted radiation.The scattering of photoluminescent emissions can be either due toagglomeration of photoluminescent phosphorescent material or as aconsequence of electromagnetic radiation scattering by of one or more ofthe additives selected to stabilize the photoluminescent phosphorescentpigment dispersion. The net result will be lower luminous intensity andpersistence.

By and large, the current practice in commercially-available materialsis to cite the luminous intensity and persistence of the underlyingphotoluminescent phosphorescent powder, rather than that of theresulting photoluminescent object. It can be recognized that forcommercial success, the important parameter is not the photoluminescentintensity and persistence of the underlying powder, but that of theresulting photoluminescent object. There is a need, therefore, to notonly develop photoluminescent phosphorescent powder materials of highperformance but also develop photoluminescent formulations that resultin photoluminescent emissions of high intensity and persistence.

Articles having inadequate reflection to the emitted electromagneticradiation, either because of surface roughness or because of their colorresulting from materials that are absorptive of photoluminescentphosphorescent emissions, can also result in degradation of luminousintensity and persistence even when high-performance formulations areapplied to such articles to create photoluminescent objects. Further,outdoor usage of photoluminescent objects also necessitates, beyond goodadhesion to substrates, mechanical robustness such as scratchresistance, etc. Specific requirements are dictated by the particularapplication, for which the use of a protective layer can also be highlybeneficial. It can therefore be seen that beyond the need to developphotoluminescent formulations of high performance, there is a need for amulti-layer system construction for applying these formulations toarticles to create photoluminescent objects of high intensity andpersistence of nighttime emissions.

The use of colorants in the form of pigments that are absorptive ofvisible electromagnetic radiation to impart daylight color tophotoluminescent formulations even when they are not absorptive ofphosphorescent emissions can result in degradation of photoluminescentintensity and persistence by virtue of either scattering ofphotoluminescent phosphorescent emissions or by inadequate charging ofphotoluminescent phosphorescent materials. The latter phenomenon canresult if the particle size of the absorptive colorants is small enough.Hence, while absorptive colorants can be used to alter the daytimeappearance of photoluminescent objects, such usage will result in alowering of luminous intensity and persistence. This is why a majorityof daylight-colored formulations are rated for low intensity andpersistence. Further, such usage also precludes the achievement ofdaytime colors and nighttime emissions being in the same family ofcolors.

U.S. Pat. No. 6,359,048 to Duynhoven discloses formulations ofphotoluminescent phosphorescent materials utilizing alkyd resins andmodified castor oil rheology modifiers. This formulation requires usinga secondary pigment particle, which, due to scattering ofelectromagnetic radiation, results in lower transmissivity ofphotoluminescent phosphorescent emissions, and thus lower perceivedintensity and persistence of emissions from objects deploying thisformulation.

U.S. Pat. No. 6,773,628 to Kinno discloses formulations ofphotoluminescent phosphorescent materials comprising syntheticcellulosic resin binders and silica-based powders used as suspendingfillers. The silica-based suspending fillers, by virtue of eitherscattering of luminescent phosphorescent emissions, or, if sufficientlysmall, by virtue of scattering of charging radiation, will result in alowering of perceived intensity and persistence of luminescent objectsdeploying this formulation.

Published U.S. Patent Application No. 2003/0222247 to Putman disclosesthe use of absorptive pigments as colorants for imparting daytime color.Again, as discussed above, on account of scattering of photoluminescentphosphorescent emissions, the intensity and persistence of nighttimeemissions from photoluminescent objects deploying this formulation willbe lowered.

U.S. Pat. No. 3,873,390 to Cornell discloses a method of makingsingle-layer photoluminescent phosphorescent or fluorescent filmsutilizing silica gel, which scatters electromagnetic radiation, todisperse the phosphorescent or fluorescent pigments. While this makesthe film translucent, again, as stated above, there will be a reductionin photoluminescent intensity and persistence. Moreover, since the resinmatrix selected for the pigments is a hot-melt adhesive, it requiresheating coating fluid to temperatures in vicinity of 2950° F. or higher.The resulting application methodology is too restrictive for manyapplications.

U.S. Pat. No. 4,208,300 to Gravisse discloses single-layerphosphorescent coatings which comprise “Crystalline charges” in amountsof 50% to 65% by weight of the phosphorescent layer. Use of such highamounts of crystalline fillers is indicative of a basic composition thathas low transmissivity to phosphor emissions without the crystallinefillers. Uses of such high amounts of filler material will not onlyresult in significantly lower concentrations of phosphorescent pigments,but also, since these fillers are silica-based, they will also result ina lowering of luminous efficiency.

U.S. Pat. No. 4,211,813 to Gravisse discloses the making of flexiblephotoluminescent articles comprising a single-layer phosphorescentcoating for applications requiring high water vapor transmissivity. Thisrequirement does not result in a degradation of the phosphor materials,since they are ZnS-based. It is now well-appreciated that thephotoluminescent intensity and persistence of ZnS-based materials issignificantly lower, as compared to the newer alkaline earth materialswhich however can be degraded by water. Hence, the need remains forconstruction of photoluminescent objects that have low water vaportransmission and still exhibit nighttime emissions of high intensity andpersistence.

U.S. Pat. No. 5,698,301 to Yonetani teaches the construction of aphosphorescent article embodying a three-layer construction, that is, areflective layer, a photoluminescent layer, and a clear protectivelayer, without use of photoluminescent fluorescent materials. Thisinvention does not require specific performance characteristics of eachof the layers. With respect to the photoluminescent layer, all that issuggested is “dispersing a phosphorescent pigment in a varnish preparedby dissolving a resin in a solvent thereby preparing an ink.” Alkalineearth materials, such as strontium aluminates, are not easy to disperseand unless one achieves a construction of such a layer withoutphotoluminescent phosphorescent particle agglomeration, there will beloss of efficiency due to incomplete charging. Also, sincephotoluminescent phosphorescent materials have high densities, withoutusing specific additives, there will be settling and compaction as thefilm dries, resulting in a lower amount of nighttime emissions from thesurface. It should also be noted that common additives for addressingthese issues, e.g., silica, scatter electromagnetic radiation, causingthe layer's transmissivity to photoluminescent phosphorescent emissionsto be lower.

U.S. Pat. No. 5,395,673 to Hunt discloses the construction of a non-slipphosphorescent surface by applying to a ground surface epoxy resincontaining compositions impregnated with phosphor pigment of the zincsulfide type. The focus of this invention is on the creation of a hardsurface with photoluminescent phosphorescent materials incorporatedtherein, and not on methodologies to maximize intensity and persistenceof nighttime emissions.

U.S. Pat. No. 5,692,895 to Franzin Nia discloses the rudimentary conceptof a photoluminescent phosphorescent orthodontic appliance utilizing theolder, zinc sulfide-type phosphors. The phosphorescent pigment can bedeposited onto the exposed bracket surfaces utilizing methods such asglazing, ion beam implantation, plasma coating, and the like. However,since the appliances are based on the older sulfide-typephotoluminescent phosphorescent materials, the resulting intensity andpersistence of the emissions will be significantly lower and, further,the materials will be subject to rapid photolytic degradation.

U.S. Pat. No. 6,207,077 to Burnell-Jones discloses the application ofphotoluminescent phosphorescent coatings to fiber optic articles using acurable layer construction, as well as a variety of fillers. The fillersinclude suspending fillers, such as silica, for preventing settling ofphosphor particles, tailoring viscosity, etc. The heavy loading offiller materials, in the neighborhood of 30%, negatively impacts theamount of photoluminescent material present, thus requiring much thickerphotoluminescent layers. In addition, due to scattering ofelectromagnetic radiation from the quantity and type of filler materialsdeployed, there will be a reduction in the intensity and persistence ofnighttime emissions from the objects deploying this formulation.

U.S. Pat. No. 6,508,732 to Romberger discloses the construction of atennis ball that includes an outer fabric cover that contains aphotoluminescent phosphorescent component. The object of this inventionis a luminescent tennis ball and not on methodologies to maximizeintensity and persistence of nighttime emissions.

Accordingly, in view of the above, there remains a need forphotoluminescent phosphorescent material formulations, photoluminescentphosphorescent objects, and methods for creating such objects, whereinthe formulations and objects not only exhibit high intensity andpersistence, but also which can be created in a variety of daytime andnighttime colors, also with high luminous intensity and persistence, andadditionally including creation of photoluminescent objects wherein thedaytime and nighttime colors are in the same family. Thephotoluminescent objects are also created to minimize photolyticdegradation, do not degrade with moisture, and are mechanically robust,particularly in outdoor applications.

BRIEF SUMMARY OF THE INVENTION

It has now been found that formulations comprising an effective amountof photoluminescent phosphorescent materials, at least one liquidcarrier medium, at least one polymeric resin, and at least oneformulation stabilizing additive, wherein said photoluminescentphosphorescent materials are uniformly distributed within saidformulation, wherein there are no additional materials that areabsorptive colorant pigments, and further wherein said stabilizingadditive is not in a solid particulate state in said liquid carriermedium provide photoluminescent phosphorescent formulations with highintensity and persistence.

Accordingly, in one of its formulation aspects, the present invention isdirected to a photoluminescent formulation comprising an effectiveamount of photoluminescent phosphorescent materials, at least one liquidcarrier medium, at least one polymeric resin, and at least oneformulation stabilizing additive, wherein said photoluminescentphosphorescent materials are uniformly distributed within saidformulation, wherein there are no additional materials that areabsorptive colorant pigments, and further wherein said stabilizingadditive is not in a solid particulate state in said liquid carriermedium.

In another one its formulation aspects, the present invention isdirected to a photoluminescent formulation comprising an effectiveamount of photoluminescent phosphorescent materials, at least one liquidcarrier medium, at least one polymeric resin, and at least oneformulation stabilizing additive, wherein said photoluminescentphosphorescent materials are uniformly distributed within saidformulation, wherein there are no additional materials that areabsorptive colorant pigments, wherein said formulation stabilizingadditive comprises a dispersing agent and a rheology modifier, andfurther wherein said stabilizing additive is not in a solid particulatestate in said liquid carrier medium.

In other formulation aspects, the present invention is directed to theforegoing photoluminescent formulations which further comprisephotoluminescent fluorescent materials, wherein said fluorescentmaterials either increase the luminous intensity or alter the emissionspectrum of the photoluminescent phosphorescent materials to not onlycreate a variety of luminous colors, but also enable the daylight colorand emission color to be in the same color family. Thesephotoluminescent formulations comprising said fluorescence-exhibitingmaterials may further comprise photostabilizers to retard photolyticdegradation of said photoluminescent materials.

In one of its object aspects, the present invention is directed to aphotoluminescent object comprising a preformed article and at least onephotoluminescent layer that results from a photoluminescent formulation.

In another one of its object aspects, the present invention is directedto a photoluminescent object comprising a preformed article, at leastone photoluminescent layer, and at least one reflective layer, whereinsaid reflective layer results from a reflective formulation, whereinsaid photoluminescent layer is distal to said preformed article, whereinsaid reflective layer is proximal to said preformed article, and whereinsaid reflective layer is characterized by a reflectance such that thetotal emission from said object is greater than 80% relative to that ofa white reflectance layer.

In yet another one of its object aspects, the present invention isdirected to a photoluminescent object comprising a preformed article, atleast one photoluminescent layer, and at least one protective layer,wherein said protective layer results from a protective formulation,wherein said protective layer is distal to said preformed article,wherein said photoluminescent layer is proximal to said preformedarticle, and wherein said protective layer has an FT of at least 95%.

In yet another one of its object aspects, the present invention isdirected to a photoluminescent object comprising a preformed article, atleast one reflective layer, at least one photoluminescent layer, and atleast one protective layer, wherein said reflective layer is proximal tosaid preformed article, wherein said protective layer is distal to saidpreformed article, and wherein said photoluminescent layer is betweensaid reflective layer and said protective layer, and wherein saidprotective layer has an FT of at least 95%.

In one of its method aspects, the present invention is directed to amethod for creating a photoluminescent object, said method comprisingthe steps of obtaining a preformed article and applying to saidpreformed article at least one photoluminescent formulation.

In another one of its method aspects, the present invention is directedto a method for creating a photoluminescent object, said methodcomprising the steps of obtaining a preformed article, applying to saidpreformed article at least one photoluminescent formulation, andapplying to said preformed article at least one reflective formulation,wherein said photoluminescent formulation is distal to said preformedarticle, wherein said reflective layer is proximal to said preformedarticle, and further wherein said reflective layer is characterized byby a reflectance such that the total emission from said object isgreater than 80% relative to that of a white reflectance layer.

In another one of its method aspects, the present invention is directedto a method for creating a photoluminescent object, said methodcomprising the steps of obtaining a preformed article, applying to saidpreformed article at least one photoluminescent formulation, andapplying to said preformed article at least one protective formulation,wherein the protective layer is distal to said preformed article,wherein the photoluminescent layer is proximal to said preformedarticle, and wherein the protective layer has an FT of at least 95%.

In yet another of its method aspects, the present invention is directedto a method for creating a photoluminescent object, said methodcomprising the steps of obtaining a preformed article, applying to saidpreformed article at least one reflective formulation, at leastphotoluminescent formulation, and at least one protective formulation,wherein said reflective layer is proximal to said preformed article,wherein said protective layer is distal to said preformed article, andwherein said photoluminescent layer is between said reflective layer andsaid protective layer, and wherein said protective layer has an FT of atleast 95%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates how absorption of ultraviolet radiation by a moleculeexcites it from a vibrational level in the electronic ground state toone of the many vibrational levels in the electronic excited state, suchas singlet states and triplet states.

FIG. 2 is a Jablonski Diagram illustrating processes that occur betweenthe absorption and emission of electromagnetic radiation.

FIG. 3 is a stylized depiction of an embodiment of the invention wherebya photoluminescent object is created using a preformed article 1 with aphotoluminescent phosphorescent layer 2 applied thereto.

FIG. 4 is a stylized depiction of an embodiment of the invention wherebya photoluminescent object is created using a preformed article 1 with areflective layer 3 and a photoluminescent phosphorescent layer 2 appliedthereto.

FIG. 5 is a stylized depiction of an embodiment of the invention wherebya photoluminescent object is created using a preformed article 1 with aphotoluminescent phosphorescent layer 2 and a protective layer 4 appliedthereto.

FIG. 6 is a stylized depiction of an embodiment of the invention wherebya photoluminescent object is created using a preformed article 1 with areflective layer 3, a photoluminescent phosphorescent layer 2, and aprotective layer 4 applied thereto.

FIG. 7 is a stylized depiction of an embodiment of the invention wherebytransfer technology is used to obtain the photoluminescent object.

FIG. 8 is a stylized depiction of an embodiment of the invention wherebya photoluminescent object is created using a preformed article 1 with areflective layer 3, a first photoluminescent phosphorescent layer 2, asecond photoluminescent phosphorescent layer 5, a first protective layer4, and second protective layer 6 applied thereto.

FIG. 9 is a stylized depiction of an embodiment of the invention wherebya photoluminescent object is created using a preformed article 1 with areflective layer 3, a first photoluminescent phosphorescent layer 2, asecond photoluminescent phosphorescent layer 5, and a first protectivelayer 4 applied thereto.

FIG. 10 is a stylized depiction of an embodiment of the inventionwhereby a photoluminescent object is created using a preformed article 1with a reflective layer 3, a first photoluminescent phosphorescent layer2, a first protective layer 4, and second protective layer 6 appliedthereto.

FIG. 11 is a stylized description of the Luminous Intensity measurementapparatus.

FIG. 12A shows the emission spectra of the photoluminescentphosphorescent layers resulting from the PF-4 formulations, with andwithout the addition of emission color-altering fluorescing compounds.

FIG. 12B shows the emission spectra of the photoluminescentphosphorescent layers resulting from PF-4 formulations wherephotoluminescent phosphorescent material H-13 has been substituted byH-14, with and without the addition of emission color-alteringfluorescing compounds.

FIG. 13A shows the reflection spectra from reflective layers of variouscolors.

FIG. 13B shows the emission spectra of the photoluminescentphosphorescent layer with reflective layers of various colors.

DETAILED DESCRIPTION OF THE INVENTION

As noted above, the present invention generally relates tophotoluminescent formulations, to photoluminescent objects comprisingpreformed articles onto which said photoluminescent formulations havebeen applied, and to methods for creating said photoluminescent objects.

However, prior to discussing this invention in detail, the followingterms will first be defined.

As used herein, “excitation” refers to the phenomenon wherein theincident radiation excites a molecule from a lower energy state to ahigher energy state.

As used herein, “luminescence” is defined as emission of electromagneticradiation.

As used herein, “photoluminescence” is luminescence occurring as aconsequence of excitation by electromagnetic radiation.

As used herein, “fluorescence” is emission of electromagnetic radiationfrom singlet excited states in which the electron in the excited orbitalis paired (of opposite sign) to the second electron in the ground stateorbital, and wherein the return to the ground state is spin allowed andoccurs rapidly by emission of a photon and wherein the emission ratesare typically 10⁻⁸ s⁻¹ with a typical lifetime around 10 nanoseconds.

“Phosphorescence” is emission of electromagnetic radiation from tripletexcited states, in which the electron in the excited orbital has thesame spin orientation as the ground state electron. Transitions to theground state are forbidden and the emissions rates are Slow.Phosphorescence lifetimes are typically milliseconds to seconds.

As used herein, “luminescent materials” are those that exhibit“luminescence.”

“Photoluminescent materials” are those that exhibit luminance as aconsequence of excitation by electromagnetic radiation.

“Photoluminescent fluorescent” materials are those which upon excitationby electromagnetic radiation exhibit fluorescence.

As used herein, “photoluminescent phosphorescent” materials are thosewhich upon excitation by electromagnetic radiation exhibitphosphorescence.

As used herein, “pigment” is a material in a solid particulate formwhich is substantially insoluble in a liquid carrier medium chosen tocarry such materials, but which can be mechanically distributed in theliquid carrier medium to modify its color and/or electromagneticradiation-scattering properties.

“Liquid carrier medium” is a liquid that acts as a carrier for materialsdistributed in a solid state and/or dissolved therein.

As used herein, a “formulation” is a liquid carrier medium, as definedabove, comprising at least one material either dissolved and/ordistributed in a solid state within said liquid carrier medium.

As used herein, “dispersion” is a formulation, as defined above, whereinsaid material is a solid distributed in the liquid carrier medium, alsoas defined above.

As used herein, a “photoluminescent fluorescent formulation” is aformulation, as defined above, which additionally comprises materialsexhibiting fluorescence that are either distributed in a solid state insaid formulation or are dissolved in said formulation.

As used herein, a “photoluminescent phosphorescent formulation” is aformulation, as defined above, which additionally comprise materialsexhibiting phosphorescence that are distributed in a solid state in saidformulation.

As used herein, a “photoluminescent formulation” is a formulation, asdefined above, which additionally comprises either photoluminescentphosphorescent materials as defined above, or photoluminescentfluorescent materials as defined above, or both.

As used herein, a “reflective formulation” is a formulation as definedabove, which comprises at least a polymeric resin in a liquid carriermedium as defined above, and further comprises at least one colorant(white or non-white).

“Stabilizing additive” is a material added to a formulation comprisingsolid particles or a dispersion, as defined above, to uniformlydistribute, prevent agglomeration, and/or prevent settling of solidmaterial in said dispersion in said liquid carrier medium to result inan enhancement of the luminous intensity. Such stabilizing additivesgenerally comprise dispersants, and/or rheology modifiers.

A “performance-enhancing additive” is a material added to a formulationcomprising solid particles or a dispersion, as defined above, to enhanceits applicability to articles to create photoluminescent objects with asmooth surface and/or to minimize scattering or surface roughness due toentrained air.

As used herein, a “protective formulation” is a formulation as definedabove, which comprises at least a polymeric resin selected forenvironmental or mechanical protection of the underlying article, uponapplication onto said article.

As used herein, a “photoluminescent phosphorescent layer” is a filmresulting from at least one photoluminescent phosphorescent formulationthat is substantially dry as characterized by the residual liquidcarrier medium being in the range of 1-5 weight % of the total weight ofthe film.

As used herein, a “photoluminescent fluorescent layer” is a filmresulting from at least one photoluminescent fluorescent formulationthat is substantially dry, as characterized by the residual liquidcarrier medium being in the range of 1-5 weight % of the total weight ofthe film.

As used herein, a “photoluminescent layer” is a film resulting fromeither a photoluminescent fluorescent, or photoluminescentphosphorescent formulation, or both, that is substantially dry, ascharacterized by the residual liquid carrier medium being in the rangeof 1-5 weight % of the total weight of the film.

A “reflective layer” is a film resulting from a “reflective formulation”as defined above, that is substantially dry, as characterized by theresidual liquid carrier medium being in the range of 1-5 weight % of thetotal weight of the film, and which is at feast substantially reflectiveof incident photoluminescent phosphorescent radiation.

A “white reflectance layer” is one that reflects 95% of visibleelectromagnetic radiation incident upon it.

A “protective layer” is a film resulting from a “protective formulation”as defined above comprising a polymeric resin that is substantially dryas characterized by the residual liquid carrier medium being in therange of 1-5 weight % of the total weight of the film. Such layersprotect photoluminescent layers and reflective layers from, for example,photolytic degradation, moisture, mechanical degradation, etc.

As used herein, “visible electromagnetic radiation” is characterized byelectromagnetic radiation with wavelengths in the region of 400nanometers (“nm”)) to 700 nm.

As used herein, “Film Transmissivity” (“FT”) is the fraction of incidentvisible electromagnetic radiation transmitted through a layer which doesnot have any photoluminescent materials.

“Photolytic degradation” is deterioration, degradation, or change inproperties, such as observed color, that is initiated by electromagneticradiation.

As used herein, “photostabilizer” materials are UV absorbers, singletoxygen scavengers, antioxidants, and/or mixtures thereof.

As used herein photopic is used to characterize luminous measurementsbased on human perception.

As used herein, “intensity” is a measure of electromagnetic radiation asperceived by the “Standard Observer” (see, e.g., C. J. Bartelson and F.Grum, OPTICAL RADIATION MEASUREMENTS, VOLUME 5—VISUAL MEASUREMENTS(1984), incorporated herein by reference for all purposes) as mimickedby a photopic detector, such as International Light Company's(Massachusetts, USA) “IL1700 Radiometer/Photometer with High GainLuminance Detector.”

As used herein, “luminous intensity” is a measure of emitted ofelectromagnetic radiation as perceived by the “Standard Observer” (see,e.g., C. J. Bartelson and F. Grum, OPTICAL RADIATION MEASUREMENTS,VOLUME 5—VISUAL MEASUREMENTS (1984), incorporated herein by referencefor all purposes) as mimicked by a photopic detector, such asInternational Light Company's (Massachusetts, USA) “IL1700Radiometer/Photometer with High Gain Luminance Detector.”

As used herein, a “preformed article” is any article onto whichphotoluminescent layers may be formed. The preformed article may berigid or flexible.

A “photoluminescent object” is any preformed article, as defined above,onto which is at least one photoluminescent phosphorescent layer isapplied.

The present invention is directed to photoluminescent formulationscomprising an effective amount of photoluminescent phosphorescentmaterials, at least one liquid carrier medium, at least one polymericresin, and at least one formulation stabilizing additive, wherein saidphotoluminescent phosphorescent materials are uniformly distributedwithin said formulation, wherein there are no additional materials thatare absorptive colorant pigments, and further wherein said stabilizingadditive is not in a solid particulate state in said liquid carriermedium.

The present invention is also directed to photoluminescent formulationscomprising an effective amount of photoluminescent phosphorescentmaterials, at least one liquid carrier medium, at least one polymericresin, and at least one formulation stabilizing additive, wherein saidphotoluminescent phosphorescent materials are uniformly distributedwithin said formulation, wherein there are no additional materials thatare absorptive colorant pigments, wherein said formulation stabilizingadditive comprises a dispersing agent and a rheology modifier, andfurther wherein said stabilizing additive is not in a solid particulatestate in said liquid carrier medium.

Generally, the photoluminescent formulations according to this inventioncontain photoluminescent phosphorescent materials in the range of about30% to about 55%, liquid carrier medium in the range of about 25% toabout 55%, polymeric resin in the range of about 15% to about 35%,stabilizing additive in the range of about 0.25% to about 20%, andperformance-enhancing additives in the range of about 0% to about 5%,based on the weight of the formulation.

The present invention is also directed to the foregoing photoluminescentformulations wherein said photoluminescent phosphorescent materials arenot radioactive and are not metal sulfide-type materials.

In another embodiment, the photoluminescent phosphorescent materials inthe foregoing formulations are alkaline-earth aluminates, alkaline-earthsilicates, alkaline-earth aluminosillicates, or combinations thereof.The photoluminescent phosphorescent materials may be metal oxidealuminates activated by europium and at least one co-activator selectedfrom the group consisting of dysprosium, lanthanum, cerium praseodymium,neodymium, samarium, gadolinium, holmium, erbium, thulium, ytterbium,lutetium, tin, manganese, and bismuth, wherein said metal is one or moreof strontium, calcium, magnesium, and barium.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the polymeric resinis selected from the group consisting of acrylates, polyvinyl chlorides,polyurethanes, polycarbonates, and polyesters, and combinations thereof.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the formulationstabilizing additive is a dispersant selected from the group consistingof acrylic acid-acrylamide polymers, or salts of amine functionalcompound and acid, hydroxyfunctional carboxylic acid esters with pigmentaffinity groups, and combinations thereof.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the formulationstabilizing additive is a polymeric urea urethane.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the polymeric resinis selected from the group consisting of acrylates, polyvinyl chlorides,polyurethanes, polycarbonates, and polyesters, and combinations thereofand wherein the stabilizing additive further comprises aperformance-enhancing additive that is a wetting agent.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the polymeric resinis selected from the group consisting of acrylates, polyvinyl chlorides,polyurethanes, polycarbonates, and polyesters, and combinations thereof,wherein the stabilizing additive further comprises aperformance-enhancing additive that is a wetting agent, and wherein theformulation has an FT of at least 95%.

In another embodiment, the present invention is directed tophotoluminescent formulations wherein the dispersing agent is selectedfrom the group consisting of acrylic acid-acrylamide polymers, or saltsof amine functional compound and acid, hydroxyfunctional carboxylic acidesters with pigment affinity groups, and combinations thereof, whereinsaid rheology modifier is a polymeric urea urethane, and further whereinsaid wetting agent is selected from the group consisting of polyethersiloxane copolymers, non-ionic organic surfactants, and combinationsthereof.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the polymeric resinis selected from the group consisting of acrylates, polyvinyl chlorides,polyurethanes, polycarbonates, and polyesters, and combinations thereof,and wherein the stabilizing additive further comprises aperformance-enhancing additive that is a wetting agent and adeaerator/defoamer.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the polymeric resinis selected from the group consisting of acrylates, polyvinyl chlorides,polyurethanes, polycarbonates, and polyesters, and combinations thereof,wherein the stabilizing additive further comprises aperformance-enhancing additive that is a wetting agent and adeaerator/defoamer, and wherein the formulation has an FT of at least90%.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein the dispersingagent is an acid-acrylamide polymer, salts of amine functional compoundand acid, hydroxyfunctional carboxylic acid esters with pigment affinitygroups, or combinations thereof, wherein the rheology modifier ispolymeric urea urethane, wherein the wetting agent is Polyether siloxanecopolymer, non-ionic organic surfactants, or combinations thereof, andfurther wherein the deaerator/defoamer is organic modified polysiloxaneswith fumed silica.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations wherein thephotoluminescent phosphorescent material is H-13, H-14, green phosphorpigment, or blue phosphor pigment, wherein the polymeric resin isNeoCryl B-818, NeoCryl B-735, NeoCryl B-813, or combinations thereof,wherein the dispersing agent is DISPERBYK-180, DISPERBYK-181,DISPERBYK-108, or Tego Disperse 710, wherein the rheology modifier isBYK-410 or BYK-411, wherein the wetting agent is Tego Wet 270 or TegoWet 500, and further wherein the deaerator/defoamer is Tego Airex 900.

In another embodiment, the present invention is direct to thephotoluminescent phosphorescent formulations which further comprisephotoluminescent fluorescent materials.

In another embodiment, the present invention is directed to theforegoing photoluminescent phosphorescent formulations comprisingfluorescent materials and further comprising photostabilizers.

In another embodiment, the present invention is directed to theforegoing photoluminescent phosphorescent formulations comprisingfluorescent materials wherein at least some of the photoluminescentfluorescent materials are excitation-altering photoluminescentfluorescent materials, wherein the excitation-altering photoluminescentfluorescent materials increase the luminous intensity of thephotoluminescent formulation.

In another embodiment, the present invention is directed to theforegoing photoluminescent phosphorescent formulations comprisingfluorescent materials wherein at least some of the photoluminescentfluorescent materials are excitation-altering photoluminescentfluorescent materials, wherein the excitation-altering photoluminescentfluorescent materials increase the luminous intensity of thephotoluminescent formulation, and wherein the fluorescent materials arein solution in the liquid carrier medium.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials wherein at least some of the photoluminescent fluorescentmaterials are emission color-altering fluorescent materials, wherein theemission color-altering fluorescent materials alter the emissionspectrum of the photoluminescent formulation to alter the perceivedcolor as compared to the perceived color prior to addition of thephotoluminescent fluorescent material.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials wherein at least some of the photoluminescent fluorescentmaterials are emission color-altering fluorescent materials, wherein theemission color-altering fluorescent materials alter the emissionspectrum of the photoluminescent formulation to alter the perceivedcolor as compared to the perceived color prior to addition of thephotoluminescent fluorescent material, and wherein the photoluminescentmaterials are in solution in the liquid carrier medium.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials that are emission color-altering fluorescent materials,wherein the emission color-altering fluorescent materials alter theemission spectrum of the photoluminescent formulation to alter theperceived color as compared to the perceived color prior to addition ofthe photoluminescent fluorescent material.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials that are emission color-altering fluorescent materials,wherein the emission color-altering fluorescent materials alter theemission spectrum of the photoluminescent formulation to alter theperceived color as compared to the perceived color prior to addition ofthe photoluminescent fluorescent material, and wherein thephotoluminescent fluorescent materials are in solution in the liquidcarrier medium.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials or fluorescent materials and photostabilizers, wherein atleast some of the photoluminescent fluorescent materials alter thedaylight color of the formulation as compared to the daylight colorwithout the photoluminescent fluorescent materials.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials or fluorescent materials and photostabilizers, wherein atleast some of the photoluminescent fluorescent materials alter thedaylight color of the formulation as compared to the daylight colorwithout the photoluminescent fluorescent materials, and wherein thephotoluminescent fluorescent materials are in solution in the liquidcarrier medium.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials or fluorescent materials in solution in the liquid carriermedium wherein at least some of the photoluminescent fluorescentmaterials are excitation-altering photoluminescent fluorescentmaterials, wherein the excitation-altering photoluminescent fluorescentmaterials increase the luminous intensity of the photoluminescentformulation, and wherein the excitation-altering photoluminescentfluorescent materials are selected from the group consisting ofcoumarins, styrylbenzenes, oxazoles, carbostyryls, stilbenes, andcombinations thereof.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials or fluorescent materials in solution in the liquid carriermedium, wherein at least some of the photoluminescent fluorescentmaterials are emission color-altering fluorescent materials, wherein theemission color-altering fluorescent materials alter the emissionspectrum of the photoluminescent formulation to alter the perceivedcolor as compared to the perceived color prior to addition of thephotoluminescent fluorescent material, and wherein the emissioncolor-altering fluorescent materials are selected from the groupconsisting of Xanthene type fluorescent dyes including rhodamine andfluorescene dyes, coumarin dyes, phenoxazone dyes including nile red,nile blue, cresyl violet, phoenoxazoles styryl type dyes, Carbostyryltype dyes, Stilbene type dyes, and combinations thereof.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials or fluorescent materials in solution in the liquid carriermedium, that are emission color-altering fluorescent materials, whereinthe emission color-altering fluorescent materials alter the emissionspectrum of the photoluminescent formulation to alter the perceivedcolor as compared to the perceived color prior to addition of thephotoluminescent fluorescent material, and wherein theexcitation-altering photoluminescent fluorescent materials are selectedfrom the group consisting of coumarins, styrylbenzenes, oxazoles,carbostyryls, stilbenes, and combinations thereof, and further whereinthe emission color-altering fluorescent materials are selected from thegroup consisting of Xanthene type fluorescent dyes including rhodamineand fluorescene dyes, coumarin dyes, phenoxazone dyes including nilered, nile blue, cresyl violet, phoenoxazoles styryl type dyes,Carbostyryl type dyes, Stilbene type dyes, and combinations thereof.

In another embodiment, the present invention is directed to thephotoluminescent phosphorescent formulations comprising fluorescentmaterials wherein at least some of the photoluminescent fluorescentmaterials are excitation-altering photoluminescent fluorescentmaterials, wherein the excitation-altering photoluminescent fluorescentmaterial is 1,4-Bis(2-methylstyryl) benzene, 7-amino-4-methylcoumrin, orcombinations thereof.

In another embodiment, the present invention is directed tophotoluminescent phosphorescent formulations comprising fluorescentmaterials or fluorescent materials in solution in the liquid carriermedium comprising photostabilizers that are Hindered Amine LightStabilizers (“HALS”) such as Tinuvin 292, Chimasorb 20202, orcombinations thereof; hydroxyphenyl triazine UV absorbers such asTinuvin 405; benzotriazole UV absorbers such as Timuvin 328;benzophenone type UV absorbers such as Chimassorb 81FL; or combinationsthereof.

In another embodiment, the present invention is directed to aphotoluminescent formulation comprising, by weight of the formulation:from about 33% to about 40% of photoluminescent phosphorescentmaterials, wherein said photoluminescent phosphorescent materials areselected from the group consisting of H-13, H-14, green phosphorpigment, and blue phosphor pigment, and wherein said photoluminescentphosphorescent materials are uniformly distributed within saidformulation; a liquid carrier medium comprising EGMME and MIBK, whereinEGMME is present in amount of about 28% to about 40%; an acrylicpolymeric resin, wherein said acrylic polymeric resin is selected fromthe group consisting of NeoCryl B-818, NeoCryl B-735, NeoCryl B-813, andcombinations thereof, and wherein the ratio of photoluminescentphosphorescent material to acrylic polymeric resin is from 1 to 2; astablizing additive, wherein said stabilizing additive comprises adispersing agent that is DISPERBYK-180, DISPERBYK-181, DISPERBYK-108, orTego Disperse 710, wherein said stabilizing additive is present inamount of about 1% to about 3%; a rheology modifier that is BYK-410 orBYK-411, wherein said rheology modifier is present in amount of about 1%to about 2%; a wetting agent that is Tego Wet 270 or Tego Wet 500present in the amount of about 0.5% to about 2.5%; and adeaerator/defoamer that is Tego Airex 900, wherein saiddearator/defoamer is present in amount of about 1% to about 3%.

In some of its object embodiments, the present invention is directed tophotoluminescent objects comprising a preformed article and at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations. In another object embodiment, the presentinvention is directed to photoluminescent objects comprising a preformedarticle, at least one photoluminescent phosphorescent layer whichresults from at least one of the foregoing formulations, and a least onereflective layer wherein said reflective layer results from a reflectiveformulation, wherein said photoluminescent layer is distal to saidpreformed article, wherein said reflective layer is proximal to saidpreformed article, and wherein said reflective layer is characterized bya reflectance such that the total emission from said object is greaterthan 80% relative to that of a white reflectance layer.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, andwherein said protective layer has an FT of at least 95%.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, and wherein theprotective layer further comprises photoluminescent fluorescentmaterials thereby resulting in a photoluminescent fluorescent protectivelayer.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, wherein the protectivelayer further comprises photoluminescent fluorescent materials, therebyresulting in a photoluminescent fluorescent protective layer, andwherein the protective layer further comprises photostabilizers.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, wherein the protectivelayer further comprises photoluminescent fluorescent materials orfluorescent materials in solution in the liquid carrier medium, therebyresulting in a photoluminescent fluorescent protective layer, orphotoluminescent fluorescent materials and photostabilizers, wherein atleast some of said photoluminescent fluorescent materials areexcitation-altering photoluminescent fluorescent materials, wherein saidexcitation-altering photoluminescent fluorescent materials increase theluminous intensity of said photoluminescent object.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, and wherein theprotective layer further comprises photoluminescent fluorescentmaterials or fluorescent materials in solution in the liquid carriermedium', thereby resulting in a photoluminescent fluorescent protectivelayer, and wherein at least some of said photoluminescent fluorescentmaterials are emission color-altering fluorescent materials, whereinsaid emission color-altering fluorescent materials alter the emissionspectrum of said photoluminescent object to change the perceived colorof said object as compared to the perceived color prior to addition ofsaid photoluminescent fluorescent material.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, wherein the protectivelayer further comprises photoluminescent fluorescent materials orfluorescent materials in solution in the liquid carrier medium, therebyresulting in a photoluminescent fluorescent protective layer, orphotoluminescent fluorescent materials and photostabilizers, wherein atleast some of said photoluminescent fluorescent materials areexcitation-altering photoluminescent fluorescent materials, wherein saidexcitation-altering photoluminescent fluorescent materials increase theluminous intensity of said photoluminescent object, and which furthercomprises emission color-altering fluorescent materials, wherein saidemission color-altering fluorescent materials alter the emissionspectrum of said photoluminescent object to change the perceived colorof said object as compared to the perceived color prior to addition ofsaid photoluminescent fluorescent material.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, with or without photostablizers, and atleast one protective layer wherein said protective layer results from aprotective formulation, wherein said protective layer is distal to saidpreformed article, wherein said photoluminescent layer is proximal tosaid preformed article, wherein said protective layer has an FT of atleast 95%, wherein the protective layer further comprisesphotoluminescent fluorescent materials, which may be soluble in theliquid carrier medium used for the photoluminescent fluorescentprotective layer, thereby resulting in a photoluminescent fluorescentprotective layer, and wherein at least some of said photoluminescentfluorescent materials alter the daylight color of said photoluminescentobject compared to the daylight color without such materials.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, wherein the protectivelayer further comprises photoluminescent fluorescent materials orfluorescent materials in solution in the liquid carrier medium, therebyresulting in a photoluminescent fluorescent protective layer, orphotoluminescent fluorescent materials and photostabilizers, wherein atleast some of said photoluminescent fluorescent materials areexcitation-altering photoluminescent fluorescent materials, wherein saidexcitation-altering photoluminescent fluorescent materials increase theluminous intensity of said photoluminescent object, and wherein theexcitation-altering fluorescent materials are selected from the groupconsisting of coumarins, styrylbenzenes, oxazoles, carbostyryls,stilbenes, and combinations thereof.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, and wherein theprotective layer further comprises photoluminescent fluorescentmaterials or fluorescent materials in solution in the liquid carriermedium, thereby resulting in a photoluminescent fluorescent protectivelayer, and wherein at least some of said photoluminescent fluorescentmaterials are emission color-altering fluorescent materials, whereinsaid emission color-altering fluorescent materials alter the emissionspectrum of said photoluminescent object to change the perceived colorof said object as compared to the perceived color prior to addition ofsaid photoluminescent fluorescent material, and wherein said emissioncolor-altering fluorescent materials are selected from the groupconsisting of Xanthene type fluorescent dyes including rhodamine andfluorescene dyes, coumarin dyes, phenoxazone dyes including nile red,nile blue, cresyl violet, phoenoxazoles styryl type dyes, Carbostyryltype dyes, Stlbene type dyes, and combinations thereof.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, wherein the protectivelayer further comprises photoluminescent fluorescent materials orfluorescent materials in solution in the liquid carrier medium, therebyresulting in a photoluminescent fluorescent protective layer, orphotoluminescent fluorescent materials and photostabilizers, wherein atleast some of said photoluminescent fluorescent materials areexcitation-altering photoluminescent fluorescent materials, wherein saidexcitation-altering photoluminescent fluorescent materials increase theluminous intensity of said photoluminescent object, and which furthercomprises emission color-altering fluorescent materials, wherein saidemission color-altering fluorescent materials alter the emissionspectrum of said photoluminescent object to change the perceived colorof said object as compared to the perceived color prior to addition ofsaid photoluminescent fluorescent material, and wherein saidexcitation-altering photoluminescent fluorescent materials are selectedfrom the group consisting of coumarins, styrylbenzenes, oxazoles,carbostyryls, stilbenes, and combinations thereof, and further whereinsaid emission color-altering fluorescent materials are selected from thegroup consisting of Xanthene type fluorescent dyes including rhodamineand fluorescene dyes, coumarin dyes, phenoxazone dyes including milered, nile blue, cresyl violet, phoenoxazoles styryl type dyes,Carbostyryl type dyes, Stibene type dyes, and combinations thereof.

In another object embodiment, the present invention is directed tophotoluminescent objects comprising a preformed article, at least onephotoluminescent phosphorescent layer which results from at least one ofthe foregoing formulations, and at least one protective layer whereinsaid protective layer results from a protective formulation, whereinsaid protective layer is distal to said preformed article, wherein saidphotoluminescent layer is proximal to said preformed article, whereinsaid protective layer has an FT of at least 95%, wherein the protectivelayer further comprises photoluminescent fluorescent materials orfluorescent materials in solution in the liquid carrier medium, therebyresulting in a photoluminescent fluorescent protective layer, orphotoluminescent fluorescent materials and photostabilizers, wherein atleast some of said photoluminescent fluorescent materials areexcitation-altering photoluminescent fluorescent materials, wherein saidexcitation-altering photoluminescent fluorescent materials increase theluminous intensity of said photoluminescent object, and wherein saidexcitation-altering fluorescent materials are selected from the groupconsisting of 1,4-Bis(2-methylstyryl) benzene, 7-amino-4-methylcoumrin,and combinations thereof.

In other object embodiments, the photostabilizers used are Tinuvin 292,Tinuvin 405, Chimasorb 20202, Timuvin 328, or combinations thereof.

In other embodiments, the present invention is directed to methods forcreating a photoluminescent object, said methods comprising the steps ofobtaining a preformed article and applying to said preformed article atleast one of the photoluminescent formulations described above.

In another method embodiment, the present invention is directed tomethods for creating a photoluminescent object, said methods comprisingthe steps of obtaining a preformed article, applying to said preformedarticle at least one of the photoluminescent formulations describedabove, and applying to said preformed article at least one reflectiveformulation, wherein said photoluminescent layer is distal to saidpreformed article, wherein said reflective layer is proximal to saidpreformed article, and further wherein said reflective layer ischaracterized by a reflectance such that the total emission from saidobject is greater than 80% relative to that of a white reflectancelayer.

In another method embodiment, the present invention is directed tomethods for creating a photoluminescent object, said methods comprisingthe steps of obtaining a preformed article, applying to said preformedarticle at least one of the photoluminescent formulations describedabove, and applying to said preformed article at least one protectiveformulation, wherein said protective layer is distal to said preformedarticle, wherein said photoluminescent layer is proximal to saidpreformed article, and wherein said protective layer has an FT of atleast 95%.

In another method embodiment, the present invention is directed tomethods for creating a photoluminescent object, said method comprisingthe steps of obtaining a performed article, applying to said preformedarticle at least one reflective formulation, applying to said preformedarticle at least one photoluminescent formulation, and applying to saidpreformed article at least one protective formulation, wherein saidreflective layer is proximal to said preformed article, wherein saidprotective layer is distal to said preformed article, and wherein saidphotoluminescent layer is between said reflective and protective layers.

The preformed article in the foregoing object and method embodimentsinclude a pathway, a pathmarker, pathway lighting, all forms of signage,an outdoor décor item, an outdoor statue, an outdoor figurine, outdoorlighting, an outdoor ornament, outdoor tree hanging parapharnelia,marine items, a boat, a buoy, instrumentation, safety gear, a helmet, ahard hat, a vest, sporting equipment, a basket ball, a tennis ball, agolf ball, a golf ball core, a golf ball cover, a baseball, a racquetball, a glove, an arm protector, a knee protector, a shoulder protector,a backboard, a sports net, recreational equipment, a swimming pool, aside of a swimming pool, the rim of a swimming pool, the bottom of aswimming pool, a holiday decoration, a candle, a floor, an umbrella, anautomobile, a wall, a stairway, an individual stair, a sidewalk, astreet, a doll, or a toy.

Selection of Binder Resin and Associated Solvent System

It is important to select only those polymeric binder resins for thephotoluminescent phosphorescent materials that do not absorbelectromagnetic radiation within the excitation spectrum of the chosenphotoluminescent phosphorescent material. This is important, forotherwise, the excitation of the photoluminescent material will beinhibited. It is also desirable that the chosen polymeric materialshould have minimal impact on the luminous intensity, that is, it shouldnot exhibit any significant quenching of the photoluminance.

Also, the liquid carrier medium can be any solvent other than water. Inselecting the liquid carrier medium, for cases wherein the polymer issoluble in said liquid carrier medium, the polymeric solution should beclear and should not exhibit any haze, otherwise, luminous intensitytransmission will be adversely impacted. In general, highly polarsolvents will increase the likelihood of emissions, and hence should, ingeneral, be avoided.

Selection of Dispersing Agents

High mechanical forces are necessary to incorporate solids in liquidmedia. It is customary to employ “dispersing agents” in order to reducethese dispersion forces and in order to keep the total energy input intothe system, which is necessary for deflocculating the solid particlesand thus the time of dispersion, as low as possible. These dispersingagents are surface-active substances of anionic, cationic, or neutralstructure. These substances are added in a small amount, either directlyto the solid or to the dispersion medium. Furthermore, it is known thateven after complete deflocculation of the solid agglomerates intoprimary particles, re-agglomeration occurs after the dispersion process.In such a case, the effort expended to produce dispersion is partiallyor completely negated. Agglomeration in photoluminescent formulationscan cause degradation in the luminous intensity and persistence eitheras resulting from incomplete excitation or due to scattering. The higherthe level of agglomeration, the higher will be the number ofphotoluminescent phosphorescent particles with a partial or no charge.

The consequences of an unstable dispersion or of re-agglomeration canalso result in a rough or non-uniform surface that can further scatterelectromagnetic radiation thereby further diminishing the luminousintensity and persistence.

There is a multiplicity of different substances which are used nowadaysas dispersing agents for pigments and extenders. A review of theexisting patent literature is given in European Patent No. 0 318 999(See, e.g., Page 2, Lines 24-26). Apart from very simple, low molecularweight compounds such as lecithin, fatty acids, and salts thereof, andalkylphenol ethoxylates, for example, complex structures are also usedas dispersing agents. In particular, these comprise amino- andamide-functional systems, which are widely-used amongst dispersingagents. In British Patent No. 2 153 804, for example, amino- andamide-functional poly- and oligocopolymers based on polyamines andpolycaprolactones are used for the dispersion of magnetic pigments.European Patent No. 0 713 894 describes the use of amino-functionalpolylactones for coatings and printing inks. Moreover, amine-functionalpolyacrylates, such as those disclosed in European Patent No. 0 311 157and in U.S. Pat. No. 3,980,602 are used for the stabilization of organicand inorganic pigments. Amine-functional polymers based onpolyisocyanates constitute a further group. See, e.g., European PatentNos. 0 159 678 and 0 438 836.

Derivatives of phosphoric acid esters are also frequently used asdispersing agents. European Patent No. 0 417 490 (see Page 2, Lines23-43) gives a summary of the use of these substances, preferably asdispersing agents or for the pretreatment of pigments. The salts ofacidic phosphoric acid esters are also described in this patent.Inorganic bases as well as mono- and di-amines are listed as the basicsalt formation components.

Low-Viscosity Prevents Mechanically-Induced Degradation ofPhotoluminescent Phosphorescent Particles

While satisfactory stabilization of pigments or solids can be achievedwith one or more of the dispersing aids cited above, many of thesedispersing agents have an insufficient capacity for reducing theviscosity on the incorporation of pigments or of solid particles inbinder vehicles. For manufacturing photoluminescent objects, there is aneed to minimize the thickness of the photoluminescent phosphorescentlayers. There is also a strong desire to reduce the amount of solvent asfar as possible (e.g., high-solids formulations). All of this can leadto high viscosity with the resulting need for the application ofexcessive energy to disperse the photoluminescent phosphorescentmaterial, which is undesirable. To summarize, excessive viscositybuildup will require applying excessive energy, which in turn will causedegradation of luminous intensity of the photoluminescent phosphorescentformulations.

Examples of suitable dispersing aids that minimize agglomeration andsuccessfully minimize viscosity buildup, that is, require very lowlevels of energy for pigment dispersion, include acrylic acid—acrylamidepolymers such as those cited in U.S. Pat. No. 6,596,816, incorporatedherein by reference for all purposes, or salts of an amine functionalcompound and an acid, such as those cited in U.S. Pat. No. 6,111,054,also incorporated herein by reference for all purposes.

Selection of Rheology Modifiers

“Rheology Modifiers” are those substances which generally can buildviscosity in liquid dispersion formulations, thereby retarding settlingof pigment materials while at the same time significantly loweringviscosity upon application of shear, to enhance smooth applicability ofsuch formulations onto articles. There is a widespread practice of usingmaterials such as colloidal silica, or fumed silica, and magnesiumaluminum silicate clays, such as bentonite, not only as thixotropicmodifiers to prevent sagging and running of luminescent formulation asit is applied to preformed articles, but also as suspending fillers,that is, for minimizing settling of dense pigment particles such asphosphor particles. See, e.g., U.S. Pat. No. 6,207,077. It should benoted that settling in the photoluminescent formulation or as theapplied formulation dries to a film to form a photoluminescent layer isundesirable as it will result in a lowering of luminous intensity.

The common practice is to use organically-modified bentonites, silicas,hydrogenated castor oil, and polyamide waxes. A disadvantage of thesesubstances is that they are mostly dry solids which have to be broughtinto the form of a semi-finished product using solvents and shearforces, and incorporated into the liquid coating system under carefultemperature control. Failure to observe such temperatures results incrystallites in the finished coating system, which may not only lead todefects in the coating, but also cause scattering and hence a reductionin the luminous intensity.

The bigger disadvantage of their use in photoluminescent formulationsand coatings to create photoluminescent layers is that they lead toturbidities and haze rather than transparent coatings, which, of course,will result in scattering of photoluminescent emissions and hence alowering of the luminous intensity and persistence. Additionally,handling dry pulverulent products which give rise to dusts in the courseof processing is undesirable. For these reasons their use as rheologymodifiers is undesirable.

The present invention employs polymeric urea-urethanes in aprotic polarsolvents as rheology modifiers. This class of rheology modifiers can beused satisfactorily, that is, without scattering of electromagneticradiation, and without excessive build up of viscosity. Use of theserheology modifiers not only minimizes settling of the dense pigmentparticle, minimizes sagging and runnability of the formulations asapplied to preformed articles, as well as assists in leveling, therebyresulting in more uniform photoluminescent layers. Examples of suchurea-urethanes can be found, for example, in U.S. Pat. No. 6,617,468 andU.S. Pat. No. 6,870,024, incorporated herein by reference for allpurposes.

Selection of Wetting Agents

If the photoluminescent formulation does not contain “wetting agents,”also known as leveling agents, the surface of the resulting layer uponapplication to an article may not be smooth. Instead, the surface may bestructured, such as having a wavy surface or as having an orangepeel-like surface. These surfaces may be finely structured, with a shortwave, or coarsely structured, with a long wave.

This waviness is unwanted not only because the surface is not visuallyappealing with a lowered market appeal, but, more importantly, anysurface structure is likely to cause scattering of electromagneticradiation and loss of luminous intensity.

Known examples of such agents are poly(meth)acrylates and polysiloxanes,which may be used as leveling promoters for coatings. In the case of thepolysiloxanes, the compounds generally comprise polydimethylsiloxanes,polymethylalkylsiloxanes, or else polyether- or polyester-modifiedpolydimethyl- or polymethylalkylsiloxanes. In the case of thepoly(meth)acrylates, preference is given to the use of polymers orcopolymers of alkyl acrylates having an alkyl radical chain length ofC₂-C₈, such as ethyl acrylate, 2-ethylhexyl acrylate, or n-butylacrylate, for example. The products used possess in some cases molecularweights of up to 100,000.

The action of all these products is based on surface activity at theliquid/gas interface: owing to a certain incompatibility with the actualbinder of the coating system, these products adopt an orientation to theinterface. This incompatibility may be increased by raising themolecular weight of these polymers. A disadvantage then, however, isthat owing to this incompatibility there can be cases wherein thescattering of electromagnetic radiation or haze of the layer becomeshigh, thereby resulting in significant reduction in luminous intensity.

The present invention employs branched polymers comprising afree-radically or ionically polymerized base molecule into whichmonoethylenically unsaturated macromonomeric units have beenincorporated by copolymerization. Examples of such polymers may be foundin U.S. Pat. No. 6,710,127, incorporated herein by reference for allpurposes.

Other Additives

Other additives, such as “deaerators” and “defoamers” may be employed.Deaerators are those substances which minimize entrained air. Defoamersare those substances that allow easier dissipation of entrained air.Depending upon the materials comprising the formulation and theresultant viscosity, a significant amount of air entrainment can causescattering of electromagnetic radiation and, hence, a reduction inluminous intensity.

The following tables and examples are offered to illustrate the presentinvention and should not be construed in any way as limiting the scopeof this invention.

Tables and Examples

Table 1 provides the material type, commercial designation, and supplierof materials suitable for use in the invention.

TABLE 1 Material Sourcing Commercial Material Type Designation(s)Supplier(s) Photoluminescent Premium Polymer Ready Set Glo,Phosphorescent Emulsion Manitoba Canada Formulation Glow PaintPhotoluminescent China Green Paint ACTCO Ltd., Taipei, PhosphorescentTaiwan Formulation Photoluminescent Green Phosphor Sun-Up Products Incof Phosphorescent Material Pigment Danvers, MA Photoluminescent LumilexGreen Honeywell Phosphorescent Material Morristown, NJ PhotoluminescentUltra Green Glow Inc. Phosphorescent Material Severn, MDPhotoluminescent H13, H14 Capricorn Chemicals, Phosphorescent MaterialEly, Cambs., England Dispersing Agent, DISPERBYK-180 BYK Chemie U.S.A.,of Formulation Stabilizing Walllingford, CT Additive Rheology Modifier,BYK-410 BYK Chemie U.S.A., of Formulation Stabilizing Walllingford, CTAdditive Wetting Agent, TEGOWET - 270 Tego Coating & Ink PerformanceEnhancing Additives of Hopewell, Additive VA Deaerator, PerformanceTEGOAIREX - 900 Tego Coating & Ink Enhancing Additive Additives ofHopewell, VA Polymeric Resin NeoCryl B-818 Neo Resins Inc Of Wilmington,MA Liquid Carrier Medium Ethylene Glycol Solvent Supplier Mono MethylEther EGME Liquid Carrier Medium Methyl Iso Butyl Solvent SupplierKetone MIBK

Table 2 provides the composition of formulations used in the followingexamples. “PF” refers to photoluminescent formulations.

TABLE 2 Composition of Formulations Formulation Example Type Number(s)Material Weight % PF-1 13 China Green Paint Commercial Formulation fromActco Ltd. PF-2 2 Premium Polymer Commercial Elumsion Glow PaintFormulation from Ready Set Glow PF-3 3, 7 Green Phosphor Pigment 38.01%PF-3 3, 7 Polymeric Resin 23.66% NeoCryl B-818 PF-3 3, 7 DispersingAgent  1.60% DISPERBYK-180 PF-3 3, 7 Rheology Modifier  1.14% BYK-410PF-3 3, 7 Wetting Agent  1.02% TEGOWET - 270 PF-3 3, 7 Deaerator  0.66%TEGOAIREX - 900 PF-3 3, 7 Liquid Carrier Medium 18.85% EGME PF-3 3, 7Liquid Carrier Medium 15.05% MIBK PF-4 8 Green Phosphor Pigment 38.01%H13 PF-4 8 All Other addenda as in Other addenda PF-3 (other than theGreen Wt % as in PF-3 Phosphor Pigment, cited above) PF-5 12 GreenPhosphor Pigment 38.01% H13 PF-5 12 Polymeric Resin 23.66% NeoCryl B-735PF-5 12 All Other addenda as in Other addenda PF-3 Wt % as in PF-3

Example 1

Three formulations, PF-3, PF-4, and PF-5, were prepared according toTable 2. Formulation PF-3 was utilized to illustrate the selection of adispersing agent according to the selection criteria presented above.Formulation PF-4 was utilized to illustrate the adverse impact ofrheology modifiers/suspending fillers that exist in a solid state in theliquid carrier medium. Formulation PF-5 was prepared using a differentpolymeric resin. It will be shown below that the formulations PF-3,PF-4, and PF-5 prepared according to this invention exhibitsignificantly higher luminous intensity. Data from these threeformulations are presented below.

Examples 2 and 13

Photoluminescent phosphorescent layer of Example 2 resulted fromcommercial green photoluminescent phosphorescent formulation obtainedfrom ACTCO, Ltd. of Taipei, Taiwan. The photoluminescent phosphorescentlayer of Example 13 resulted from photoluminescent phosphorescentformulation obtained from Ready Set Glow. Luminous data from thephotoluminescent layers are presented below.

Luminous Intensity Measurement

Luminous Intensity measurements were performed according to theapparatus set up described in FIG. 11. The luminous intensitymeasurements were performed on a photoluminescent layer on a whitereflective substrate. The reported data are normalized for layerthickness and hence, the reported luminous intensity measurements inmcd/meter² are presented for a layer of one-thousandth of an inch (a“mil”, or 25 micron thickness).

Samples were charged by exposure to a 600 watt UV/visible light source(UV Wash, Elation Lighting, Los Angeles, Calif.) for 10 minutes. Thesamples were then immediately inserted into the emission measuringapparatus described in FIG. 11. A 2 inch circular aperature (12.57square inches) is placed between the sample and detector with a 12 inchdistance between the sample and detector. Emission was measured over aperiod of 30 minutes after exposure. The high gain photometric detectoris connected to the IL1700 photometer (International Light, Inc).

Film Transmission Measurement (“FT”)

Transmission measurement of films coated on clear 5 mil Mylar base wereperformed using a Greytag Spectrolino spectrophotometer in reflectancemeasuring mode. The sample to be analyzed was placed on a whitereflective layer and reflectance was measured between 510 and 550 nm.Percent transmission was calculated relative to the transmission of aclear mylar base without any coated films.

Photoluminescent phosphorescent formulations of high luminous intensitycan only result from ensuring that the photoluminescent phosphorescentmaterial is uniformly distributed in the liquid carrier medium, does notexhibit agglomeration and settling, either as a formulation or as alayer on an article. Further, any materials likely to exist in a solidstate in the formulation can scatter electromagnetic radiation, andtherefore reduce luminous intensity. Such materials should therefore beat least minimized, but preferably avoided. Such materials can beelectromagnetic radiation-scattering pigments, such as TiO₂ or otherabsorptive colorant pigments to enhance daylight color, or suspendingfillers such as silica powder or clays, etc.

For the reasons cited above, this invention does not utilize absorptivepigment colorants in photoluminescent phosphorescent formulations tomodify and/or enhance daytime color of photoluminescent phosphorescentlayers or photoluminescent fluorescent layers or protective layerscomprising photoluminescent fluorescent materials.

Furthermore, all of the formulation stabilizing additives, such asdispersants and rheology modifiers, as well as the performance-enhancingadditives, such as wetting agents, deaerators, etc. are selected so asto minimize scattering of electromagnetic radiation and use of excessiveenergy so that luminous intensity of photoluminescent layer ismaximized.

Examples 4, 5, 6, and 7

Examples 4, 5, 6, and 7 are based on photoluminescent layers resultingfrom formulation PF-3 with none to varying dispersing agents. Table 3provides dispersant selection data for maximizing luminous intensity ofa green phosphor powder supplied by Sun Up Products of Danvers, Mass.

TABLE 3 Dispersing Agent Impact On Luminous Intensity Example 5 Example6 (Formulation (Formulation Example 4 See Below) See Below) (FormulationDispersing Dispersing Elapsed See Below) Agent Agent Example 7 Time NoDispersing Stabilizing Stabilizing Formu- After Agent Additive Additivelation Cessation Stabilizing DISPERBYK- Tego Disperse- PF-3 of Additive108 710 Luminous Excitation Luminous Luminous Luminous Intensity InIntensity Intensity Intensity mcd/ Minutes mcd/meter² mcd/meter²mcd/meter² meter² 2 Minutes 117.31 120.96 128.09 130.47 4 Minutes 61.7363.38 66.94 68.47 6 Minutes 41.99 43.09 45.49 46.43 8 Minutes 31.7432.55 34.26 35.03

In Example 4, the formulation used is PF-3 minus the addition of anydispersing agent. In Example 5, the formulation used is PF-3 with thedispersing agent being DISPEWRBYK-108. In Example 6, the formulationused is PF-3 with the dispersing agent being Tego Disperse-710.

Thus it can be seen that whereas use of DISPERSYK 108 results in a smallincrease in luminous intensity for the selected phosphor, DISPERBYK-180can result in a luminous intensity gain of approximately 11%, comparedto the case wherein no dispersing agent is used. It should be noted thatwe have not reported data for dispersants which resulted in badlyagglomerated preparations. Even though all of these dispersants resultedin formulations that looked uniform visually they caused differences inluminous intensity.

Examples 8, 9, 10, and 11

Examples 8, 9, 10, and 11 are based on photoluminescent layers resultingformulation PF-4 as described in Table 2. These examples serve toillustrate the adverse impact on luminous intensity resulting from theuse of rheology modifiers/suspending fillers that exist in the solidstate in the liquid carrier medium. We begin by first presenting filmtransmissivity (FT) data in Table 4. We will then show in Table 5 thatluminous intensity data generally track the FT data and hence can serveas a useful guide for screening rheology modifiers.

TABLE 4 Impact of Light Scattering Rheology Modifiers On FilmTransmission Rheology Rheology Rheology Rheology Modifier ModifierModifier Modifier Alumina at BYK-410 Garamite Silica 5% Transmission99.12% 94.17% 95.38% 94.17% Through 2 Mil Thick Film (FT %)

TABLE 5 Impact of Light Scattering Rheology Modifiers On LuminousIntensity Example 9 Example 10 Example 11 Example 8 (Formulation(Formulation (Formulation PF-4 See See Note See Note Elapsed TimeFormulation Note Below) Below) Below) After Rheology Rheology RheologyRheology Cessation of Modifier Modifier Modifier Modifier Excitation InBYK-410 Garamite Silica Alumina Minutes (mcd/m²) (mcd/m²) (mcd/m²)(mcd/m²) 2 Minutes 162.77 145.47 142.36 134.53 4 Minutes 84.92 75.8574.00 69.06 6 Minutes 58.00 51.51 50.18 46.79 8 Minutes 44.00 39.0638.00 35.28

In Example 9, the formulation used is as in PF-4 with the BYK-410 beingreplaced by Garamite clay at 5% sourced from Southern Clay Products ofTexas. In Example 10, the formulation used is as in PF-4 with theBYK-410 being replaced by Silica Powder, Cabosil PS-720 at 5%. InExample 11, the formulation used is PF-4 with the BYK-410 being replacedby alumina oxide from Alfa Aesar at 0.5% (20-50μ.

It can be seen from Table 4 that FT measurements, that is, transmissionmeasurements in a non-phosphorescent layer as defined above, is a goodway to screen the impact of the additives. This is validated in Table 5with a measurement of Luminous Intensity. Depending on the additive,there is a decrease in Luminous Intensity of approximately between 11and 20%. Of course, addition of higher amounts as reported in prior artwill lead to even greater losses.

Examples 3, 8, and 12

Examples 3, 8, and 12 illustrate photoluminescent formulations accordingto this invention together with comparative examples of commercialapplications.

TABLE 6 Comparison of Luminous Intensity Of PhotoluminescentPhosphorescent Layers According to this Invention with CommercialMaterials Example 13 Elapsed Com- Time Example Example 2 mercial AfterExample 3 Example 8 12 Commercial Formu- Cessation Formu- Formu- Formu-Formulation lation of lation lation lation Ready Set China ExcitationPF-3 PF-3 PF-5 Glo Paint In Minutes (mcd/m²) (mcd/m²) (mcd/m²) (mcd/m²)(mcd/m²) 2 Minutes 130.47 162.77 172.39 81.02 81.27 4 Minutes 68.4784.92 89.30 41.59 42.45 6 Minutes 46.43 58.00 60.00 28.18 28.73 8Minutes 35.03 44.00 45.07 21.25 21.76

Thus, our first object in the preparation of photoluminescent materialsis to select the polymeric resin and its solvent system together withthe dispersants, rheology modifier and wetting agent (comprising thestabilizing additive package), to be used for creating a uniformhomogeneous photoluminescent phosphorescent particle liquid dispersion,such that when all of these materials, that is the polymeric resin andits solvent system together with the stabilizing additives are coatedonto a 50 micron transparent film, they are characterized by a visibleelectromagnetic radiation transmission of greater than 95%.

The next step is to gently add the photoluminescent phosphorescentpigment powder to the liquid mixture comprising polymeric resin and itssolvent system, together with the stabilizing additives described aboveunder slow agitation. With the proper selection of the ingredientsaccording to the criterion discussed earlier and the addition ofphotoluminescent phosphorescent particles under low shear one cansuccessfully create a dispersion free of agglomeration and which willresult in high luminous intensity formulations and as applied ontoarticles with a reflectance layer having high reflectivity as describedabove will also result in photoluminescent objects of high luminousintensity as seen in Examples 3, 8, and 12.

Use of Photoluminescent Fluorescers to Increase Luminous Intensity andPersistence

We have found that when certain Photoluminescent fluorescing materials(Ultra Violet absorbers) are chosen so that their emission has at leasta partial overlap with the absorption of photoluminescent phosphorescentmaterials, surprisingly result in an increase in the luminous intensity.

Alkaline earth photoluminescent materials generally have an excitationband in the range of 365 to 400 nm. Even though many excitation sourcessuch as sunlight have adequate energy in this spectrum, it has beensurprisingly found that the additional incorporation of Photoluminescentfluorescent materials, such as described above, results in emissions ofhigher intensity.

It appears that the use of UV absorbers that absorb the shorterwavelength UV spectrum to reemit in the longer wavelength UV spectrum,thereby resulting in a greater amount of the photoluminescentphosphorescent material excitation energy in the longer wavelengths, inturn may result in greater efficiency of emission with a correspondingincrease in luminous intensity and persistence.

Example 14

Example 14 is a photoluminescent layer resulting from the incorporationof a photoluminescent fluorescent material in formulation PF-3.

TABLE 7 Increase in Luminous Intensity With Excitation-AlteringFluorescent Material Example 14 Formulation Elapsed Time Example 3 PF-3After Cessation Formulation with addition of Photoluminescent ofExcitation In PF-3 Fluorescent Fluorescent Minutes mcd/m² MaterialMaterial added 2 Minutes 130.47 174.50 1,4-bis(2-methylstyryl) 4 Minutes68.47 86.05 benzene added to 6 Minutes 46.43 57.20 protective overcoat 8Minutes 35.03 42.60 at 0.5%

Emission Color-Altering Fluorescent Materials

The emission color of the photoluminescent phosphorescent layers orobjects can be altered by the addition of certain fluorescing compoundsto the photoluminescent phosphorescent layer or to the protective layerabove it. Key properties of these fluorescing compounds is that theirspectral absorption overlaps the spectral emission of the phosphor andthat the fluorescing compounds have minimal spectral absorption in theregion in where the phosphor charges. FIG. 12A shows the emissionspectra of the photoluminescent phosphorescent layers resulting fromPF-4 formulations with and without the addition of emission coloraltering fluorescing compounds.

Similarly, FIG. 12B shows the emission spectra of the photoluminescentphosphorescent layers resulting from PF-4 formulations wherein thephotoluminescent phosphorescent material H-13 is substituted by H-14,with and without the addition of emission color altering fluorescingcompounds

Referring to FIG. 12, in the first graph, FIG. 12A, the green phosphoremission of photoluminescent layer, curve (1), can be shifted to yellowor light orange by adding 0.005% w/w % (on photoluminescentphosphorescent material) rhodamine 6G to Formulation PF-4, curves (2)and (3), respectively. The net color emission is a result of thecombined emissions of the fluorescent compound and any remainingemission (not absorbed by the fluorescent compound) of thephosphorescent material. Curve (4) is the emission curve for aphotoluminescent phosphorescent layer resulting from addition of 0.015%w/w % (on photluminescent phosphorescent material) sulfarhodamine B toFormulation PF-4, and curve (5) is the emission of a photoluminescentphosphorescent layer resulting from addition of 0.024% w/w % (onphotoluminescent phosphorescent material) rhodamine 6G and 0.006% w/w %sulfarhodamine B to formulation PF-4. The resulting emission colors arelight pink and reddish orange, respectively.

Again referring to FIG. 12, FIG. 12B shows the impact addition ofphotoluminescent fluorescent materials on the emission of aphotoluminescent phosphorescent layer resulting from formulation PF-4with phosphorescent material H-13 substituted by H-14.

Photolytic Stability of Photoluminescent Fluorescers to Alter ExcitingRadiation

The photoluminescent fluorescent compounds selected to enhance theluminous intensity and persistence of photoluminescent phosphorescentmaterials can be subject to photolytic degradation and may additionallyrequire the use of photostabilizers to retard the photolyticdegradation.

The following prophetic examples, A-D, serve to illustrate the inventionwith regard to retarding the photodegradation of the photoluminescentfluorescent compounds as set forth above.

Example A

The addition of Tinuvin 292 HP(HALS) (1-3 wt %) to a PF-4 formulationcontaining 0.5 wt % of the fluorescing compound1,4-bis(2-methystyrl)benzene will reduce by 50% the photodegradation ofsaid fluorescing compound arising from 10,000 foot candle solar exposurefor 48 hours.

Example B

The addition of Chimassorb 2020 (HALS) (1-3 wt %) to a PF-4 formulationcontaining 0.5 wt % of the fluorescing compound coumarin 120 will reduceby 25% the photodegradation of said fluorescing compound arising from10,000 foot candle solar exposure for 48 hours.

Example C

The addition of Chimmassorb 2020 (HALS) plus the addition of 0.01 to 0.1wt % of a UV absorber of either the benzotriazole, benzophenone, orhydroxyphenyl triazine class to a PF-4 formulation containing 0.5 wt %of the fluorescing compound coumarin 120 will reduce by 50% thephotodegradation of said compound arising from 10,000 foot candle solarexposure for 48 hours.

Example D

The addition of a 0.01 to 0.1 wt % of a UV absorber of either thebenzotriazole, benzophenone, or hydroxyphenyl triazine class to a PF-4formulation containing 0.05 wt % of the fluorescing compound nile blueperchlorate will reduce by 50% the photodegradation of said compoundarising from 10,000 foot candle solar exposure for 48 hours.

Reflective Layer

The brightness of the photoluminescent phosphorescent layer is afunction the reflectance of the underlying surface of the article towhich a photoluminescent formulation is applied to create aphotoluminescent layer. Article surfaces can vary widely in theirproperties and can result in significant absorption or minimumreflection of emission that is ineidient upon such a surface. Thecreation of a reflective layer with high reflectance of photoluminescentemission onto which is then applied is a photoluminescent phosphorescentlayer can then serve to ensure high luminous intensity.

More specifically, the important property of the reflective layer is thereflectance in the wavelength region where the photoluminescentphosphorescent layer emits. In general, the photoluminescentphosphorescent layer emits 50% of its radiation toward the viewer and50% of its radiation toward the reflective layer. If the reflectivelayer reflects 100% of the emission from the photoluminescentphosphorescent layer, the net emission reaching the view would be 100%,assuming no other losses such as those from scattering. If thereflective layer reflects 0% of the emission from the photoluminescentphosphorescent layer, the net emission reaching the viewer would be 50%(50% radiation emitted directly at the viewer+0% reflected by thereflected layer). If the reflective layer reflects 50% of the emission,the net emission reaching the viewer is 75% (50% directly emitted at theviewer+0.5*50% reflected or 25%). Table 8, below, shows net impact ofreflective layer reflectance on net emission reaching the viewer.

TABLE 8 Net Impact of Reflective Layer Reflectance On Net EmissionReaching the Viewer Net Emission % Emission Emitted Reflective LayerFrom Reflective Direcly at Total Emission Reflectance Layer Viewerreaching viewer 100%   50% 50%  100% 75% 37.5% 50% 87.5% 50%   25% 50%  75% 25% 12.5% 50% 62.5% 0%   0% 50%   50%

To illustrate this, a photoluminescent phosphorescent layer coated on aclear base was placed on top of reflective layers of different colors(based on the MacBeth Color Checker) and the net emission was measuredas a function of the reflective color. The following graph shows thereflectance spectra of the colors evaluated The emission curve for thephotoluminescent phosphorescent layer containing a green phosphor isoverlayed on the graph, FIG. 13A, to illustrate the region where highreflectance is most important. FIG. 13B shows the emission spectra ofthe photoluminescent phosphorescent layer with different coloredreflective layers.

The following table, Table 9, shows the actual integrated emission ofthe photoluminescent phosphorescent layer relative to the whitereflective layer. The table also shows the % reflectance that isweighted based on the emission curve of the phosphor which was used topredict emission % relative to the white reflector layer.

bluish white green 1 green 2 green 3 black magenta cyan green Actual100.00% 81.08% 62.32% 63.17% 52.14% 55.73% 64.89% 83.54% Emission %relative to White

The objective in choosing an appropriate reflective layer to be used fora given photoluminescent phosphorescent layer is of course, maximize theluminous intensity but also to permit flexibility of reflective layercolors. Given this objective, for reflective layers according to thisinvention, the goal is to have a total emission greater than 80%relative to that of a white reflectance layer as defined above. It canthen be seen from the table above that for the photoluminescentformulation selected (PF-4), this is achieved for reflective layers thatare white, green one, and bluish green.

1. A photoluminescent object comprising: a preformed article; and atleast one photoluminescent layer that results from a formulation thatcomprises an effective amount of at least one phosphorescent material; aliquid carrier medium; a polymeric resin; a formulation stabilizingadditive comprising a rheology modifier; the formulation also comprisingan effective amount of at least one fluorescent material; wherein thephosphorescent material is substantially uniformly distributed withinthe formulation; an emission spectrum of the photoluminescentformulation prior to the addition of the fluorescent materialconstituting a primary emission; the primary emission resulting in aperceived daytime color and a perceived nighttime color.
 2. Thephotoluminescent object of claim 1, wherein at least some of thefluorescent material is primary emission altering material that altersat least one of perceived daytime color and perceived nighttime color ofsaid photoluminescent object and wherein, spectral absorption of atleast some of the fluorescent material overlaps spectral emission of atleast some of the phosphorescent material, the spectral absorption of atleast some of the fluorescent material being lower in a spectral regionwhere the phosphorescent material charges.
 3. The photoluminescentobject of claim 1, further comprising: a reflective layer resulting froma reflective formulation disposed beneath the photoluminescent layer,the reflective layer exhibiting a reflectance such that emission fromthe object is greater than 80% relative to that of a white reflectancelayer.
 4. The photoluminescent object of claim 3, wherein at least someof the fluorescent material in the layer is a primary emission alteringfluorescent material that alters at least one of perceived daytime colorand nighttime color of the photoluminescent object; wherein spectralabsorption of at least some of the fluorescent material overlapsspectral emission of at least some of the phosphorescent material, thespectral absorption of said at least some of the fluorescent materialbeing lower in a spectral region where the phosphorescent materialcharges.
 5. The photoluminescent object of claim 1, wherein thefluorescent material is in solution in the liquid carrier medium.
 6. Thephotoluminescent object of claim 1, wherein at least some of thefluorescent material in the photoluminescent layer isexcitation-altering material that increases a luminous intensity of theformulation; an emission spectrum of at least some of the fluorescentmaterial at least partially overlapping an absorption spectrum of atleast some of the phosphorescent material.
 7. The photoluminescentobject of claim 6, wherein at least some other of the fluorescentmaterial in the layer is a primary emission altering material thatalters at least one of perceived daytime color and perceived nighttimecolor of the object and wherein spectral absorption of at least someother of the fluorescent material overlaps spectral emission of at leastsome of the phosphorescent material, the spectral absorption of thefluorescent material being lower in a spectral region where thephosphorescent material charges.
 8. The photoluminescent object of claim6, further comprising: at least one reflective layer that results from areflective formulation disposed beneath the photoluminescent layer,wherein the reflective layer exhibits a reflectance such that the totalemission from the object is greater than 80% relative to that of a whitereflectance layer.
 9. The photoluminescent object of claim 1, whereinthe phosphorescent material is selected from a group comprising ofalkaline-earth aluminates, alkaline-earth silicates and alkaline-earthaluminosilicates.
 10. The photoluminescent object of claim 1, whereinthe fluorescent material is provided in solution in the liquid carriermedium.
 11. The photoluminescent object of claim 1 wherein thephosphorescent material comprises a metal sulfide.